In industry, there are numerous instances where a protective coating is utilized to reduce deleterious effects of the environment upon sensitive items. For example, various electronic apparatus is adversely affected by moisture that degrades insulation, initiates corrosion of parts, etc. Other devices are similarly damaged by vapors within the local environment, such as acid fumes, etc. Even in the medical field, constituents of the environment are often found to be detrimental due to various reactions.
It has been common practice in industry that, when the various items are potentially damaged by the environment, some form of coating is applied to reduce the potential interaction. Typically, various organic coatings are applied, one commonly-utilized coating being a parylene. Other similar organics (polymers and epoxys) are also utilized. Another form of protective coating utilized in industry is a metal or ceramic layer; typically, aluminum being the metal utilized.
Although these coatings have been generally satisfactory, long-term exposure to detrimental constituents often results in damaging of the coated item. This is particularly the case when the item is relatively easily attacked by corrosion, etc. The exact nature of the penetration of the coating by the damaging constituent is not always known; however, in the case of metal coatings, the metal tends to have pin-holes (possibly due to the columnar structure) in the layer due to the deposition techniques that are utilized for its application. Similarly, the organic layers are often penetrated by diffusion and/or small pin-holes.
Accordingly, it is an object of the present invention to provide a more impermeable coating for critical items to prevent penetration by deleterious components of the local atmosphere.
It is another object of the present invention to provide a coating for critical items, the coating deriving a synergistic result from a combination of diffusion barrier materials and physical barrier materials.
Another object of the present invention is to provide a coating for critical items, the coating deriving a synergistic result from alternating diffusion barrier layers and physical barrier layers.
A further object of the present invention is to provide a coating for critical items wherein the coating comprises multiple and alternating layers of an organic substance and a metal.
It is also an object of the present invention to provide a coating for critical items wherein the coating comprises multiple and alternating layers of a polymer and a ceramic.
Another object of the present invention is to provide a coating for critical items where the coating comprises multiple and alternating layers of a polymer and aluminum.
An additional object of the present invention is to provide a coating for critical items where a portion of the coating is a diffusion barrier material selected from polymers, carbon exhibiting properties equivalent to diamond amorphous carbon and silicon, together with a portion being a physical barrier material selected from metals and ceramics.
These and other objects of the present invention will become apparent upon a consideration of the following full description of the invention.